Algin is a complex hydrocolloid obtained from brown seaweed such as (Laminaria, Macrocystis, Ascophyllum, and the like. It is precipitated by acid and is soluble in aqueous alkaline media wherein the alkalinity is due to the presence of alkali metals or ammonium. However, in the presence of certain di- and trivalent cations it is insoluble. For example, water soluble sodium alginates react with soluble calcium salts to form insoluble calcium alginate gels. Furthermore, the preferential affinity exhibited by algin for calcium rather than sodium, can be enhanced by the inclusion of an ionizing compound of calcium such as a weak acid in common solution with the sodium alginate.
Alginate gels are used in a wide variety of food preparation technologies, especially those associated with the production of desserts, jellies, pie fillings and the like. They are also used to stabilize and to otherwise modify the rheology of food sols during various food production procedures. One of their more useful properties is their ability to form chemically, rather than thermally, induced gels. These gels result from the intermolecular association of the above noted di- and trivalent cations with the dimerically associated guluronic acid block regions of the alginate molecules. Again, calcium ions are generally regarded as superior to other polyvalent ions in their interaction with algin, particularly in the context of food systems. Specific examples of the application of this chemical mechanism can be found in the preparation of a wide variety of fruit jams, jellies, jellied salads, and jellos such as those produced by the interaction of various alginates with calcium carbonate in the presence of sodium tripolyphosphate and adipic acid.
The literature discloses that most of the specific applications of the algin/calcium gel reaction to food technologies are carried out in the context of an aqueous media. For example, U.S. Pat. No. 2,441,729 discloses the manufacture of gels from water soluble algin, calcium salts, and weak acids such as acetic or citric acid, in conjunction with a gel retarding salt such as sodium hexametaphosphate. A similar, aqueous media, algin gel reaction is disclosed in U.S. Pat. No. 2,918,375 wherein adipic or fumaric acid is employed as the acid ingredient. These patents point out how, upon addition of such acids to an aqueous mixture of sodium alginate and a calcium salt, the calcium salt is ionized to yield calcium ions which, in turn, react with the soluble alginate to form insoluble calcium alginate. Calcium sulfate, gypsum and dicalcium phosphate are some of the more commonly used edible sources of calcium used in such processes.
As noted above, alginate gel compositions containing citric acid, water soluble alginate salts, calcium salts and sodium hexametaphosphate were once marketed in the form of dry, jello mixes, activated by the addition of water. These dry mix products were not altogether satisfactory however, chiefly because of their package instability. For reasons which were not clearly understood, the citric acid reacted with the calcium salt in the dry mix. Consequently, when the packaged materials were added to water they would not consistently form a gel. In an effort to overcome this problem with these citric acid-alginate gels, an attempt was made to use fumaric acid in lieu of citric acid. This approach was not altogether successful either because the fumaric acid-containing gels were found to be too grainy when hard water was used in their preparation. In an effort to solve the problems created by the use of fumaric acid in the alginate gels, an attempt was made to use adipic acid in lieu of fumaric acid. Adipic acid was found to be satisfactory in some respects but created other problems. For example, it was found that alginate gels containing adipic acid and a calcium phosphate salt gave a gel having a somewhat cloudy appearance. In an attempt to overcome this problem, it was found that the use of calcium carbonate as the calcium source rather than calcium sulfate or dicalcium phosphate gave a gel having the improved clarity required in a dessert gelatin. However, the use of adipic acid in a alginate gel created a further problem in that it produced a gel which had a disagreeable tartness. Although a certain degree of tartness is a desirable characteristic in some dessert gels, the tartness of adipic acid gels is very disagreeable in the context of other dessert items. It is even more disagreeable in the context of other nondessert food items, particularly meat products. In order to overcome this problem in the context of producing jellos, it was found that the use of sodium tripolyphosphate as a sequestionary in lieu of the sodium hexametaphosphate previously employed reduced the tartness of the gel to an acceptable level. U.S. Pat. No. 3,455,701 discloses a resulting gel mix containing a water soluble alginate, calcium carbonate, sodium triphosphate, and adipic acid. This mixture resolves the various problems encountered in the prior art by providing a package stable gel mix, a homogeneous gel which did not have a grainy consistency, a gel having the desired clarity for a dessert gel, and a gel whose taste was not disagreeably tart, at least in the context of dessert gels.
However, all of the above noted algin/calcium reaction gel mechanisms have been largely eschewed in the context of structured meat products. This follows from the fact that the tart flavors imparted by many of the calcium ionizing acids used in jello type products are objectionable in meat products. It also follows from the fact that the otherwise too rapid release of calcium during the aqueous mixing of desserts which is controlled by the use of certain calcium sequestrants cannot be similarly controlled in the context of structured meats. This is because the typical edible sequestrants used in dessert gel preparations, e.g., sodium hexametaphosphate, tetrasodium pyrophosphate and sodium citrate tend to impart severe off flavors to meat products even though their taste characteristics are not objectionable in the tart or sweet context of gelatin desserts, pie fillings, ice cream, milk puddings, frozen fruits and the like. Consequently, phosphate salts, such as sodium hexametaphosphate, sodium pyrophosphate and sodium tripolyphosphate are generally only added to processed meat products when other ingredients in such products can effectively mask the off flavors otherwise imparted by the phosphate salts. For example, bologna often contains phosphate salts at levels up to 0.5%. However, bologna products also generally have 2-3% sodium chloride present and/or spice mixes which tend to mask the off flavors imparted by the phosphate salts. However, since algin/calcium products do not generally contain sodium chloride and/or spice mixes, the off flavors imparted by such phosphate salts are usually detectable by the average consumer. Furthermore, for any given level of alginate and calcium salt, an increase in the level of sequestrant causes a progressively weaker final gel, since the ultimate distribution of the calcium ions between the alginate and sequestrant increasingly favors the latter. In other words, conversion of the sodium alginate into the gelled calcium form is progressively reduced and the resultant gel is progressively weakened in its structure. Such structural weaknesses are much less acceptable in the context of structured meat products, than they are in other types of gels.
However, some limited, and very specialized variations of the algin/calcium reaction have been successfully applied to the preparation of certain meat products. For example, dog and cat foods have been produced by variations of the algin/calcium reaction. These variations are well summarized in United Kingdom Pat. No. 1,474,629. They begin with a mixing of a finely divided mix or emulsion of animal and/or vegetable protein containing materials with an alginate. After forming, these products are then sprayed with an aqueous solution of a water soluble calcium salt. The calcium ions in the spray react with the algin near the surface of the product to form a skin on the outside of the product which is strong enough to enable it to withstand subsequent rough production handling. In a further variation of this process, a sparingly soluble calcium salt can also be added to the mix or emulsion in order to form a soft gel inside the strong skin. The final product, normally a gel of low grade meats, offals and/or vegetable proteins, is designed to simulate chunks of meat or meatballs. This process is not, however, well suited for the production of meat products intended for human consumption. There are a number of reasons for this. For example, the chunks or meatballs manufactured by the process of United Kingdom Pat. No. 1,474,629 are not intended to stick together with other meats or coagulated water soluble proteins. On the contrary, individual chunks or balls are the desired form of the end product of this process. In the context of human consumption however, an end product wherein actual chunks of meat are bound to other chunks of meat to form larger pieces rather than individual chunks or balls, makes for a far more desirable product form. Similarly, the skin produced by such a calcium chloride spray and the soft, high water content inner portions of these chunks or balls, are unacceptable to humans with respect to their inherent texture of "mouth feel". Furthermore, the concentrations of the calcium chloride spray needed to produce a skin capable of "encapsulating" the softer interior of these products are such that they impart severe off flavors which are unacceptable to human beings.
However, other specialized variations of the algin/calcium reaction have been specifically directed to food products intended for human consumption. They have met with varying degrees of success. For example, U.S. Pat. No. 3,769,027 teaches the production of a meat glazing material comprised of a hydrolyzate, fat, algin, a food grade phosphate, a food grade source of calcium and flavoring materials. The resulting powder is coated onto uncooked food stuff such as meat and during cooking the powder forms a continuous film or coat having a glazed appearance. This results in a meat having an attractive appearance and texture and also serves to seal in the juices of the meat during cooking and thereby keeping the meat moist and tender.
U.S. Pat. No. 3,395,024 teaches another coating process designed to retard spoilage in meat, seafood, poultry and the like. The process provides for the coating of food products, including meats, with an aqueous algin dispersion containing a carbohydrate comprising at least one sugar selected from the group consisting of monosaccarides and disaccarides dissolved in water. The coated product is then subjected to an aqueous gelling solution containing a water soluble source of calcium ion in order to bond the coating to the food product but without imparting any bitter taste thereto.
Such coatings have not, however, found great commercial acceptance or usage. They usually give an undesirable taste to cooked meats. Such prior art coatings also do not uniformly adhere to the meat product to which they are applied and they tend to crack and spall during storage and handling. Clear coating materials using mainly corn, carbohydrates and algin have been suggested as an alternative for increasing storage life, preserving quality and reducing moisture loss, but the use of such materials has not found great acceptance in the meat preparation industry. While such coating materials may improve the meat's texture and juiciness, and in some cases its color, appearance, surface texture and odor over uncoated products, the flavor for such coated products is decidedly inferior. This is largely due to the bitter flavor imparted by the calcium gelling solution when it is used in the context of converting the above-noted starch solutions to plastic-like coatings.
In view of the above difficulties encountered in trying to apply the algin/calcium reaction to meat products, structured meat products are currently produced by another technology, i.e., the technology used in making sausage. In sausage products, cohesion between meat pieces is accomplished by formation of a traditional myosin heat-set protein matrix following extraction of muscle proteins and subsequent heat treatment. These structured products must be marketed either frozen or precooked in order to retain their structural integrity. Sodium chloride and phosphate salts are used during the mechanical manipulation of such products in the extraction of the muscle proteins which are thereafter involved in the heat-set gelation. However, even though the traditional myosin heat-set gelation mechanism provides adequate binding of structured meat products in the cooked state, it is of little functional significance in the binding of uncooked meat pieces. These salt-phosphate structured meat products have other disadvantages as well. Prior to cooking, they must be kept frozen in order to retain their structural integrity. Furthermore, the addition of sodium chloride accelerates development of oxidative rancidity and, thus, off flavor and off odor development; sodium chloride is also known to cause discoloration of raw meat products. Finally, addition of sodium chloride and certain phosphates is now regarded as undesirable to certain consumers due to diet/health considerations.
Clearly then, structured meat products, particularly structured raw meat products, without high sodium chloride concentrations would provide a number of benefits to the meat marketplace since consumers generally prefer purchasing meat cuts in the raw, refrigerated state; consequently, algin/calcium structured meat products would have a definite retail marketing advantage over current myosin heat-set structured products. Furthermore, since freezing of such products would not be required, energy savings can be realized during the marketing and final cooking of meat products from a raw, rather than from a frozen state. Moreover, production of structured meat products using the algin/calcium gel mechanism does not require addition of sodium chloride or phosphates for effective binding. Hence, the detrimental effects of sodium chloride on oxidative rancidity rates and discoloration of refrigerated and frozen structured products can be avoided. Sodium sensitive individuals would also benefit from the production of structured meat products low in sodium content. The possible adverse effects of bone decalcification due to the presence of phosphates would also be avoided. Algin/calcium structured meat products would also possess many of the other advantages provided by current structured meat products. The meat industry would enjoy extensions of product lines, added value to trimmings and increased marketing alternatives. Consumers would enjoy new products intermediate in price and quality to ground meat and intact muscle portions as well as products available with variable fat levels. Such algin/calcium structured meat products would also prove useful in pre-cooked structured meats intended for microwave cooking. Our methods could be applied to a wide variety of meats intended for human consumption including but not limited to, chops, steaks, roasts, appetizers, fast food entrees and the like as well as seafood and poultry products.